It has been known for many years that many organic materials will decay or decompose in time by either an aerobic process in the presence of oxygen or by an anaerobic process in the absence of oxygen. Aerobic and anaerobic decomposition processes are both naturally occurring biochemical processes that have been utilized for many decades.
The products of anaerobic decomposition include carbon dioxide (CO.sub.2), methane (CH.sub.4), and nitrogen rich solids, usually dispersed or dispersable in water, usuable as a fertilizer or soil conditioner. Methane has is an odorless, colorless, lighter-than-air gas that is commonly contained in natural gas. (Odor typically is added to natural gas to facilitate its detection.)
Anaerobic decomposition processes require an oxygen-free environment maintained at an elevated temperature. Insulated containers therefore may be used to accommodate and even hasten the naturally occurring decomposition process.
Generally in the United States and other highly industrialized countries, the prospect of processing waste materials to produce usable fuel alternatives have not been fully exploited. Research and development activities relating to waste materials typically have been concentrated on alternatives for safely disposing of such waste materials. Many of the projects undertaken for producing anaerobic digestion systems have concentrated on small scale digesters for the production of small amounts of methane gas by digestion of waste materials.
With our continuing dependence on fossil fuels and the most recent concern for the environment and the "greenhouse effect" that may be occurring due to the excess carbon dioxide emissions from the burning of these fossil fuels, it would be desirable to have a system and process for the efficient production of methane gas by anaerobic decomposition of suitable organic materials for use as an energy source for the future.